The subject matter herein relates generally to pluggable connectors that have signal contacts configured to convey data signals and ground contacts that control impedance and reduce crosstalk between the signal contacts.
Communication systems exist today that utilize pluggable cable assemblies to transmit data. For example, network systems, servers, data centers, and the like may use numerous cable assemblies to interconnect the various devices of the communication system. Cable assemblies may include a pluggable connector that is configured to be inserted into a receptacle assembly. The pluggable connector includes signal contacts and ground contacts in which the signal contacts convey data signals and the ground contacts control impedance and reduce crosstalk between the signal contacts. In differential signaling applications, the signal contacts are arranged in signal pairs for carrying the data signals. Each signal pair may be separated from an adjacent signal pair by one or more ground contacts.
There has been a general demand to increase the speeds at which data is transmitted through the communication systems. As data rates increase, however, it becomes more challenging to maintain a baseline level of signal quality. For example, crosstalk may occur between adjacent signal contacts or adjacent signal pairs. In addition to crosstalk, electrical energy that flows along the surface of each ground contact may form a field that propagates between the ground contacts. The fields may couple with each other to support an unwanted electrical propagation mode that is repeatedly reflected and forms a resonating condition (or standing wave). Electrical noise caused by the resonating condition may increase return loss and/or crosstalk and reduce throughput.
To reduce the electrical noise, it has been proposed to electrically common the ground contacts using a metal conductor or a lossy plastic material. The effectiveness and/or cost of implementing these techniques is based on a number of variables, such as the geometries of the signal and ground contacts within the pluggable connector. These techniques, however, may not sufficiently reduce the crosstalk that occurs between signal contacts or signal pairs.
Accordingly, there is a need for pluggable connectors that reduce crosstalk between signal contacts and reduce electrical noise caused by resonating conditions in ground contacts.